Bearings – Rotary bearing – Plain bearing
Reexamination Certificate
2000-01-28
2001-06-05
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Plain bearing
C384S291000
Reexamination Certificate
active
06241394
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a walk mechanism for a dragline. The invention also relates to lubrication of journal bearings.
BACKGROUND OF THE INVENTION
A walking dragline typically includes a main housing and a boom that extends upwardly and outwardly from the main housing and has thereon a sheave for supporting a hoist rope. The hoist rope extends from a bucket hoist mechanism and over the sheave to a bucket for causing vertical movement of the bucket. A drag rope extends between a bucket drag mechanism and the bucket for causing horizontal movement of the bucket. The main housing is supported by a tub that sits on the ground when the dragline is engaged in digging operations. Two matching walk mechanisms are mounted on opposite sides of the main housing and are operable for moving the main housing over the ground between digging operations.
U.S. Pat. No. 5,245,882 discloses a walk mechanism of typical construction. A walk mechanism ordinarily includes a shoe for engaging the ground during walking movement. The shoe is fixed to a walk leg housing that is mounted on an eccentric. The eccentric is fixed to a main walk shaft and rotates at about one revolution per minute. The eccentric is connected by a knee link to the main housing through a journal bearing and a pin fixed to the main housing, such that rotation of the eccentric causes the walk leg housing to pivot, thereby causing walking movement of the shoe. The motion of the knee link relative to the pin is oscillatory and pivotal. The journal bearing facilitates the pivoting movement between the knee link and the pin.
U.S. Pat. No. 5,320,431 discloses a walk mechanism journal bearing design typical of prior art constructions. Various grease groove arrangements have been tried to provide effective lubrication within the bearing. Those shown include opposed sine waves, axially-directed grooves, and angled grooves cut into the interior cylindrical surface of the bearing.
For proper function and life, a suitable film of lubricant should always be present between a bearing surface and the mating contact surface in the area of relative motion. To accomplish this, a predetermined amount of lubricant is forced into a groove pattern that carries the lubricant to the desired areas. If the lubrication system fails or does not provide adequate mounts, all surfaces in contact may not have the proper film thickness during operation. The end result could be accelerated wear of both the bearing and the mating surface.
One problem with conventional dragline walk mechanisms is wear on the walk mechanism components, particularly the journal bearing, that is compounded by the relative inaccessibility of the journal bearing. The wear is due in large part to inadequate lubrication in the bearing, and to insufficient bearing surfaces in the highest-loaded regions of the bearing.
SUMMARY OF THE INVENTION
The invention provides a journal bearing with improved features that give it a longer duration between maintenance outages.
In particular, the invention provides a journal bearing comprising a generally cylindrical outer surface and a generally cylindrical inner surface. The inner surface includes an inner edge, an outer edge, and a midline defined as a circumferential line midway between the inner edge and the outer edge. The inner surface also includes a least-loaded region and a highest-loaded region, and a first groove pattern symmetric about the midline, the pattern extending from the least-loaded region to the highest-loaded region. The pattern includes a lubricant entry point on the midline in the least-loaded region, a lubricant reservoir on the midline on the opposite side of the highest-loaded region from the lubricant entry point, and substantially more grooving in the least-loaded region than in the highest-loaded region.
In addition, the invention provides a journal bearing comprising a generally cylindrical outer surface and a generally cylindrical inner surface. The inner surface includes an inner edge, an outer edge, and a midline defined as a circumferential line midway between the inner edge and the outer edge. The inner surface also includes a first groove pattern, the groove pattern being symmetric about the midline, the pattern including a lubricant entry point on the midline, a lubricant reservoir on the midline, a generally diamond-shaped outer groove having first, second, third, and fourth groove segments, each groove segment being oblique to the midline, the first and second groove segments meeting at the lubricant entry point, the third and fourth groove segments intersecting at the lubricant reservoir, the first and second groove segments connecting with the third and fourth groove segments, respectively, and a substantially semicircular inner groove extending between the first and second groove segments and having a concave side facing the lubricant entry point.
The invention provides a groove pattern in which lubricant is substantially always available in the grooves regardless of the amount injected.
The invention also provides a groove pattern such that, even with small oscillatory rotational or pivotal movement between the bearing and the mating surface, lubricant is spread over a high percentage of the surface.
The invention also features a groove pattern design including a lubricant entry point and a lubricant reservoir that has the advantage of limiting wear in the bearing due to the bearing's ability to store, collect, and distribute an adequate amount of lubricant within the bearing.
The invention also features a groove pattern design that limits the amount of grooves in the regions of highest loading in the bearing to ensure that sufficient bearing surface is available to carry the load.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.
REFERENCES:
patent: 1940301 (1933-12-01), Grobel et al.
patent: 2901297 (1959-08-01), Sternlicht
patent: 3881788 (1975-05-01), Kotauczek
patent: 4105267 (1978-08-01), Mori
patent: 5245882 (1993-09-01), Kallenberger et al.
patent: 5320431 (1994-06-01), Kallenberger
patent: 5600905 (1997-02-01), Kallenberger et al.
Kallenberger Harvey J.
Zawlocki Mark R.
Hannon Thomas R.
Hurnischfeger Technologies, Inc.
Price David R.
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